Endovascular graft for providing a seal with vasculature

ABSTRACT

A graft provided with a flexible sealing member to substantially prevent blood from leaking between the graft a lumen into which the graft is placed. In one embodiment, the flexible sealing member may be pressed against the vascular wall by an outwardly biased spring means attached to the sealing member. In other embodiments, the sealing member may be self-positioning upon deployment of the graft. The sealing member also may be formed into the shape of a toroid, which may be filled with thrombogenic material causing blood permeating into the toroid-shaped space to coagulate therein and hold the sealing member in place. It is also contemplated that the sealing member be formed from tufts of frayed yarn protruding circumferentially from the outer surface of the graft. A method of manufacturing such tufted yarn sealing members is also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of U.S. patentapplication Ser. No. 10/796,543, filed on Mar. 8, 2004, which is adivisional application of U.S. patent application Ser. No. 09/559,681,filed on Apr. 27, 2000 (now U.S. Pat. No. 6,729,356, which issued on May4, 2004).

BACKGROUND OF THE INVENTION

The present invention relates generally to medical devices, and moreparticularly to methods and apparatus for the endoluminal placement oftubular prostheses, such as grafts, for repairing aneurysms or othervascular defects in humans and animals.

Aneurysms are discrete dilations of the arterial wall, caused byweakening of the arterial wall. One of the most common, and among themost life threatening, is an aneurysm of the abdominal aorta between therenal and iliac arteries. If untreated, the aneurysm dilatesprogressively with an ever increasing risk of rupture and hemorrhagicdeath.

One method of treatment is provided by direct surgical intervention, inwhich the defective vessel may be bypassed or replaced using aprosthetic device such as a synthetic graft. The risks involved indirect surgical intervention of this magnitude are great, and include anextensive recovery period.

In recent years a less invasive method of treatment has evolved througha series of inventions. The details vary, but, conventionally, aresilient tubular conduit fashioned from flexible fabric (hereinreferred to as a “graft”) is introduced into the defective vessel bymeans of catheters introduced into the femoral artery. The graft isattached to the non-dilated or slightly dilated arteries above and belowthe aneurysm using expandable metallic cylinders (herein referred to as“attachment systems”) which may include barbs or hooks to enhanceattachment to the vascular wall.

When an attachment system is positioned on the interior of a graft'slumen, it will tend to cause the outer wall of the graft to pressagainst the inner wall of the vessel, thereby providing the additionalfunction of providing a seal, preventing fluid flow to the regionbetween the graft and the vascular wall.

However, the use of generally cylindrical grafts to reinforce vascularwalls in a patient is not without problems. Grafts are required to becompressed into a catheter before being delivered and deployed intofinal position. Furthermore, grafts compressed into a catheter fordelivery must be capable of bending around corners and branches of thepatient's vascular system. The graft must accordingly be sufficientlyflexible to satisfy these requirements.

One of the challenges encountered with the use of a flexible graft isthat, because a diseased vessel is often irregularly shaped, the ends ofthe graft, even when urged outwardly by an attachment system, may nothave a continuous circumferential edge pressed firmly against the innerwall of the vessel. As a result, fluid may leak into or out of (througha branch vessel) the region between the graft and the vascular wall,thereby increasing fluid pressure on the weakened walls of the vesseland reducing the protective effect of the graft. The same problem willoccur if, as a result of an error in pre-operative sizing of thediseased vessel, a graft is provided that has a diameter slightlysmaller than the diameter of the diseased vessel. Moreover, in the eventthe target vessel changes shape over time (i.e., increase in neckdiameter or shrinkage in aneurysm), perigraft flow may occur. It will beappreciated that in these situations, because the fabric from whichgrafts are conventionally made is not circumferentially expandable, acomplete seal around the circumference of the vessel will likely not beachieved.

Accordingly, there is a need for an improved graft that provides anenhanced seal for substantially preventing the flow of blood into theregion between the graft and the vascular wall.

SUMMARY OF THE INVENTION

Briefly, and in general terms, an intraluminal graft in accordance withthe present invention is structured to provide an enhanced seal betweenthe graft and the wall of a lumen within which the graft is implanted.The graft of the present invention generally comprises a tubular member,at least one expandable attachment system connected to the tubularmember, and at least one expandable sealing member connected to anexterior wall of the tubular member.

In one aspect of the invention, the graft of the present invention isadapted to be radially compressed to a reduced diameter to facilitateinsertion into a patient's vasculature and for advancement within thevasculature to a desired location. The graft is further adapted to beradially expandable from its compressed condition to an expandedcondition for engagement with the vascular wall, and thus, the graft iscontemplated to be made from a biocompatible material. In furtherembodiments, the graft may be bifurcated to have left and rightbranches, each with an opening at an inferior end.

The attachment system of the present invention is configured to have agenerally cylindrical profile, and is adapted to be radially compressedto a reduced diameter. The attachment system is radially expandable fromits compressed condition to an expanded condition, to facilitateimplantation of a graft within vasculature. At least one attachmentsystem is connected to the wall of the graft, at a superior end portionthereof. In further embodiments, additional attachment systems may beconnected to the graft to provide additional attachment to the vascularwall as desired.

According to one embodiment of the present invention, a sealing membermanufactured from a generally flexible fabric and having afrusto-conical shape is connected to an exterior wall of the tubularmember of the graft. The sealing member is supported by a biasing memberwhich may be formed from a generally undulating wire frame configured toprovide the frusto-conical profile of the sealing member and to impartan outward bias sufficient to compress the sealing member against thevasculature. The sealing member advantageously provides the graft withthe ability to expand to assume the shape of the vasculature at thetarget site, thereby preventing fluid flow into the region between thegraft and the vascular wall.

In a second embodiment of the invention, the graft is configured with asealing member that is adapted to cooperate with the outward expansionof an attachment system of the graft so that, upon deployment of thegraft, the sealing member is moved from a first position remote from theattachment system to a second position overlapping the attachmentsystem. In the deployed state, the sealing member of this embodimentcooperates with fluid flow to enhance the seal between tubular memberand vascular wall. Additionally, tufted yarn possibly impregnated withthrombogenic material may be attached to the sealing member, therebyfurther enhancing the sealing effect.

In a third embodiment, the improved graft is adapted with a sealingmember that has a flexible disk configuration. In this embodiment, agenerally undulating biasing member provides the sealing member with anoutward bias. The outward bias of the wire frame causes the sealingmember to be pressed against the wall of the vessel, substantiallypreventing leakage between sealing member and vascular wall.

In a fourth embodiment, there is provided a disk-shaped sealing member,an outer circular edge of which is configured with a wire hoop biasingmember. The wire hoop biasing member is packed into a delivery capsuleby folding the hoop into a generally zig-zag shape. When deployed fromthe delivery capsule, the wire hoop unfolds into a circular profile tothereby substantially prevent leakage between sealing member andvascular wall.

In a fifth embodiment, the sealing member has a toroid shape, the outersurface of which is made from a flexible fabric, and the interior ofwhich may be filled with a thrombogenic material such as polyesterfilaments. It is to be recognized that the seal fabric may be very thincompared to graft since the seal fabric only needs to initiate clotting.The toroid-shaped sealing member is configured to fill with thepatient's blood which will subsequently coagulate with the thrombogenicmaterial, thereby creating a rigid obstacle to the flow of blood betweensealing member and the vascular wall. In another aspect of theinvention, thrombogenic filling material may be introduced into thetoroid-shaped interior of the sealing member after the graft has beendelivered to a desired position in the patient's vasculature.Additionally, small apertures may be created in a wall between the graftand sealing member so that the sealing member fills with blood flowingfrom the interior of the graft.

In a sixth embodiment, the sealing member may be formed entirely fromtufts of yarn which are fixed to the outer surface of the graft. Amethod of manufacturing such a graft is also disclosed.

Other features and advantages of the present invention will becomeapparent from the following detailed description, taken in conjunctionwith the accompanying drawings, which illustrate, by way of example, theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view, depicting one embodiment of a graft ofthe present invention, configured with a frusto-conical sealing member;

FIG. 2 is a cross-sectional view, taken along line A-A of FIG. 1;

FIG. 3 is a perspective view, depicting an alternative embodiment of anattachment system;

FIG. 4 is a perspective view depicting a biasing member;

FIG. 5 is a perspective view, depicting a second embodiment of a graftconfigured with a frustrum-shaped sealing member;

FIG. 6 is a top view of the graft shown in FIG. 5;

FIG. 7 is a perspective view of the graft shown in FIG. 5 in a deployedstate;

FIG. 8 is a top view of the graft shown in FIG. 7;

FIG. 9 is a perspective view, depicting a variation of the embodiment ofthe graft of FIG. 5;

FIG. 10 is a perspective view of the graft shown in FIG. 9 shown in adeployed state;

FIG. 11 is a cross-sectional view, depicting a third embodiment of thegraft of the present invention configured with a disk-shaped sealingmember;

FIG. 12 is a sectional view taken along lines B-B of FIG. 11;

FIG. 13 is a perspective view, depicting a fourth further embodiment ofthe graft of the present invention, configured with a disk-shapedsealing member;

FIG. 14 is a sectional view taken along lines C-C of FIG. 13;

FIG. 15 is a perspective view of the graft shown in FIG. 11, in acompressed condition;

FIG. 16 is a cross-sectional view, depicting a fifth embodiment of thegraft of the present invention configured with a toroid-shaped sealingmember;

FIG. 17 is a cross-sectional view, depicting the graft of the presentinvention configured with a variation of a toroid-shaped sealing member;

FIG. 18 is a cross-sectional view, depicting the graft of the presentinvention configured with another variation of a toroid-shaped sealingmember;

FIG. 19 is a cross-sectional view, showing the graft of FIG. 18 with atube disposed therein;

FIG. 20 is a perspective view, depicting a sixth embodiment of the graftof the present invention configured with tufts;

FIG. 21 is a perspective view, depicting a variation of the graft shownin FIG. 20;

FIG. 22 is a side view, depicting a graft of the present invention;

FIG. 23 is a cross-sectional view, depicting a manufacturing stepinvolving the graft shown in FIG. 22; and

FIG. 24 is a perspective view of the graft shown in FIG. 23 afterfurther processing.

DETAILED DESCRIPTION OF THE INVENTION

In general, the present invention involves configuring a graft with asealing member that operates to occupy spaces between the graft and alumen into which the graft is implanted. The preferred embodiments ofthe improved graft are described below. Although the descriptions setforth below generally relate to configuring a proximal end of a graftwith a sealing member, the improvement may be applied to the distal endof a graft as well. Where the graft is bifurcated, the disclosed sealingmembers may be applied to any or all of the ends of such a graft. Theterm “proximal” as used herein shall mean upstream, while “distal” shallmean downstream.

FIG. 1 exemplifies a proximal end portion of one embodiment of a graft30 of the present invention positioned within a vessel 32 of a patient.The vessel 32 is shown to expand from a relatively narrow diameterhealthy section to a dilated section where the tissue is diseased. Theimproved graft 30 comprises a tubular member 34 having a proximal end 36and distal end (not shown in FIG. 1), at least one expandable attachmentsystem 38, and a generally frustrum-shaped sealing member 40 supportedby a biasing member 44. The attachment system 38 is connected to thetubular member 34 adjacent the proximal end 36 of the graft 30.

As shown in FIGS. 1 and 2, the sealing member 40 includes an innercircumferential edge 41 and an outer circumferential edge 42, the innercircumferential edge 41 being connected to an outside surface of thetubular member 34. In one embodiment, the point of connection betweenthe sealing member 40 and tubular member 34 is longitudinally separatedfrom the attachment system 38, so as to minimize the outer profile ofthe graft assembly 30 when it is compressed for insertion intovasculature.

The tubular member 34 and the sealing member 40 are contemplated to bemanufactured from any flexible surgical implantable material such asDacron™ which is known to be sufficiently biologically inert,non-biodegradable, and durable. One material found to be satisfactory isDeBakey soft woven Dacron™ vascular prosthesis (uncrimped) sold by USCI.In order to prevent the woven material from unraveling at the ends, theends can be melted with heat to provide a small melted bead of Dacron™.

The attachment system 38 may be either self expanding orballoon-expanded, and may be connected, preferably, but not necessarily,to an inner wall of the tubular member 34. As shown in FIG. 1, theattachment system 38 may have a plurality of hooks 43 connected to it toenhance attachment to the vascular wall. The attachment system 38 ismade from a wire formed into an undulating configuration definingopposing apices. In a preferred embodiment, the apices include helicalsprings 45.

With reference to FIG. 3, there is shown an alternative embodiment of anattachment system 46. In this embodiment, the attachment system 46includes hooks 47 which are integrally formed at proximal apices 48. Theattachment system 46 is further characterized by having a semi orgenerally flat wire configuration, in that members 49 have a depth thatis greater than its width. In a preferred method of manufacture, theflat wire attachment system 46 is contemplated to be laser cut from atube.

With reference to FIG. 4, the biasing member 44 may be formed from awire which follows a generally undulating path, producing a plurality ofalternating inner apices 56 and outer apices 58 which are joined byconnecting members or legs 60. The biasing member 44 has a generallyfrusto-conical profile and is shown connected to the inside surface ofthe sealing member 40; however, it can alternatively be attached to anoutside surface. The biasing member 44 serves to urge the sealing member46 from a first compressed position to a second expanded position. Whenthe biasing member 44 is compressed stored energy tends to urge legs 60and apices 56, 58 radially outward in a direction generally at a rightangle to a longitudinal axis of the device. The biasing member 44provides a continuous and outwardly directed urging force, pressing thesealing member 40 against the diseased vascular wall 32, to therebyobstruct the flow of blood into the region between the tubular member 34and the vascular wall 32.

The generally undulating shape of the wire frame forming the biasingmember 44 also serves to facilitate compression of the biasing member 44when it is placed within a delivery capsule (not shown). The compressionof the biasing member 44 may be accomplished by compressing the biasingmember 44 within its elastic limit. Placing selected inner and outerapices 45 in different planes aids in reducing the size to which thebiasing member 44 can be compressed. Additionally, incorporating helicalsprings 62 at the apices 56, 58 aids in the self-expansion of thebiasing member 44. For tubular members 34 configured with largerdiameter sealing members 40, the biasing member 44 can be provided withadditional apices 56, 58 to enhance the sealing effect.

The biasing member 44 may be formed of a corrosion resistant materialthat has good spring and fatigue characteristics. One such materialfound to be particularly satisfactory is Elgiloy™ which is achromium-cobalt-nickel alloy manufactured and sold by Elgiloy of Elgin,Ill. Another suitable material is Nitinol.

It will be appreciated that the biasing member 44 has the ability toautomatically adjust to various shapes of diseased vessel walls 32 orchanges in anatomy shape or position over time. This ability is animportant design feature, because it may not be possible to accuratelypredict the shape of the diseased vessel 32 into which the improvedgraft 30 is delivered, and also because the wall of the diseased vessel32 may undergo changes in shape due to cardiac pulsation or othermovements of the patient. By adjusting to the actual profile of thediseased vessel wall 32, the biasing member 44 and the sealing member 40substantially prevent leakage of blood into the region between tubularmember 34 and vessel wall 32.

The biasing member 44 may be secured to the sealing member 40 bysuitable connecting means 65, such as Dacron™ polyester sutures, bywhich the biasing member 44 may be sewn or stitched onto the sealingmember 40. Connection can be accomplished by sewing suture material intoand out of the wall of the sealing member and by forming knots on one ormore of the biasing member's legs 50. The attachment system 38 may besimilarly connected to the tubular member 34 using polyester sutureconnecting means 65.

Turning now to FIGS. 5-8, another embodiment of an improved graft 130 ofthe present invention is described. The graft 130 embodies a tubularmember 134, an attachment system 138, and a sealing member 140. Theattachment system 138 may embody the undulating wire or flat wireconfiguration described above, or any other suitable expandable framearrangement. The attachment system 138 is connected to the tubularmember 134, adjacent a proximal end thereof.

The sealing member 140 has a generally frusto-conical shape with aninner circumferential edge 141 and an outer circumferential edge 142.The inner circumferential edge 141 is connected at an outside surface ofthe tubular member 134. Additionally, pieces of tufted yarn 157,preferably impregnated with a thrombogenic substance, may be attached tothe sealing member 140. The point of connection between tubular member134 and sealing member 140 is preferably positioned medical to theattachment system 138 to keep the compressed diameter of the assemblysmall.

As shown in FIGS. 5 and 6, to facilitate packing the improved graft 130into a delivery tube device (not shown), the tubular member 134 andsealing member 140 are positioned in first compressed conditions,wherein the outer circumferential edge 142 of the sealing member 140 isfolded away from the proximal end 136 of the tubular member 134. Foldingthe sealing member 140 in this manner has the advantage of reducing theoverall outside profile of the graft assembly 130 when it is placed in acompressed condition. At least one thread 154 with first end 156 andsecond end 158 (See FIG. 8) is provided and are attached to the outercircumferential edge 142 of the sealing member 140. The second ends 158of the threads 154 are first passed sequentially through a number of theouter eyelets 151 formed at the proximal apices of the attachment system138, and are then connected to the graft 130. It is contemplated that amonofilament polypropylene thread 154 can be employed, and that theoptimal number of threads to use in order to avoid entanglement isthree.

It will be appreciated that when the graft 130 is deployed from itscompressed condition and the attachment system 138 is activated toexpand outward, the first ends 156 of the threads 154, together with theouter edge 142 of the sealing member, are pulled toward the proximal end136 of the tubular member. Thus, the sealing member 140 in its deployedstate, overlaps the attachment system 138 to thereby benefit from theoutward bias of the attachment system 138 and to sealingly engage thevasculature. It will be appreciated that the tufted yarn 157 attached tothe sealing member 140 can enhance the seal with the vascular tissuewhen compressed against the tissue by the attachment system 138.Additionally, it is also to be recognized that the tubular yarn 157 mayalso bunch up at the attachment system 138 and still work as intended.

The number of outer eyelets 151 through which the second ends 158 of thethreads 154 are passed will depend on the displacement required to movethe outer circumferential edge 142 of the sealing member from its firstundeployed position to its final deployed position. The amount ofproximal axial displacement that the first end 156 of each thread willexperience upon expansion of the attachment system may be expressed as(D_(expanded)−D_(compressed))*θ_(wrap)/2, where D_(expanded) is thediameter of the attachment system 138 in expanded condition,D_(compressed) is the diameter of the attachment system 138 incompressed condition, and θ_(wrap) (See FIG. 8) is the angle (inradians) extended to the center of the attachment system by that portionof thread 154 which winds around the circumference of the attachmentsystem passing through the eyelets 151.

A variation of the graft 130 shown in FIGS. 5-8 is depicted in FIGS. 9and 10. In this embodiment, a first end 256 of each thread 254 isconnected to a point on the sealing member 240 between an inner edge 241and an outer edge 242. It will be appreciated that as so configured, thesealing member 240 will be pulled proximally as the attachment system238 expands, but that the outer edge 242 will extend distally of thepoint of connection between thread 254 and sealing member 240. Thus, ina deployed condition, there are two layers of fabric between a vascularwall and the tubular member 230. Consequently, a thicker layer of tuftedmaterial 257 may be sandwiched between the vascular wall and the tubularmember 230 to facilitate forming a seal.

With reference to FIG. 11, another embodiment of an improved graft 430of the present invention is shown. In this embodiment, the tubularmember 434 and attachment system 438 have a similar configuration as thesame of the previously described embodiments. The tubular member 434 isconnected to a sealing member 440 supported by a wire frame biasingmember 444. The sealing member 440 may be made from the same flexiblematerial as the sealing members of the previous embodiments, allowingthe sealing member to assume both a compressed condition and an expandedcondition. The sealing member 440 of this embodiment, however, has adisk shape with an inner circumferential edge 441 and an outercircumferential edge 442.

As exemplified in FIG. 12, the inner circumferential edge 441 of thesealing member 440 is continuously connected to an outer surface of thetubular member 434. The point of connection between tubular member 434and sealing member 440 is preferably positioned so as not to coincidewith the attachment system 438. The wire frame biasing member 444 may bemade of the same wire material as the biasing members of the previousembodiments and accordingly, may have a frusto-conical shape.Alternatively, as shown in FIG. 11, it is contemplated that the biasingmember 440 can define a generally cylindrical expanded profile, withalternating inner apices 446 and outer apices 448 joined by struts 450.When the wire frame 444 is compressed, stored energy tends to urge thestruts 450 and apices 446, 448 of the wire frame 444 radially outward.

The inner apices 446 of the wire frame biasing member 444 is attached tothe outer circumferential edge 442 of the sealing member 440, the outerapices 448 being allowed to protrude in an inferior direction. Thebiasing member 444 is adapted to provide an outward bias to the sealingmember 440, thereby causing the outer edge 442 of the sealing member 440to press against the diseased vascular wall 32, and substantiallyprevent leakage of blood between the tubular member 434 and the vascularwall 32.

As shown in FIGS. 13-15, another embodiment of a graft 530 of thepresent invention includes a disk-shaped sealing member 540. In thisaspect of the invention, the sealing member 540 may be supported by awire hoop 562 with a generally radially outward spring bias. The outercircumferential edges 542 of the sealing member 540 is contemplated tobe connected to the wire hoop 562. Connection may be achieved by anysuitable means such as by stitching the two elements together withpolyester filaments.

As shown in FIG. 15, the wire hoop 562 may be compressed for loadinginto a delivery capsule (not shown), by configuring the hoop 562 into agenerally zig-zag shape. The wire hoop 562 may be made of a corrosionresistant material with good spring properties, such as Nitinol™. Thewire hoop 562 is fabricated to have a diameter slightly larger than thatof the blood vessel 32, so as to provide a continuous contact therewithand to substantially prevent leakage of blood between tubular member 534and a vessel wall 32.

Yet a further embodiment of an improved graft 631 is shown in FIG. 16.The graft 631 of this embodiment includes a tubular member 634 as wellas an attachment system 638 similar to that of the previous embodiments.In this embodiment, a toroid-shaped sealing member 666 which may be madefrom thrombogenic material, is fixed to an outer wall of the tubularmember 634. The sealing member 666 may be sufficiently porous to permitblood to percolate through it. A compressible thrombogenic material 672may be introduced into an interior of the toroid-shaped sealing member666. When deployed in the patient, it is contemplated that blood willslowly permeate through the porous fabric of the sealing member 666 andcoagulate with the thrombogenic material 672 to thereby stiffen thesealing member 666. This results in forming a seal between the tubularmember 634 and the vascular wall 32.

Further, it is contemplated that the sealing member 666 may be made fromplanar fabric which is initially generally rectangular, with superiorends 674 and inferior ends 678 and two lateral edges 668, 670. Thesuperior 674 and inferior ends 678 are continuously circumferentiallyconnected to the outer wall of the tubular member 634. The lateral edges668, 670 are connected to each other, thereby forming an enclosedtoroid-shaped space in which the wall of the tubular member 634 partlyencloses the toroid-shaped space. This form has the advantage ofminimizing the number of fabric layers the graft 631 will have in itscompressed condition.

In another form of the toroid-shaped sealing member 766 (FIG. 17), thesealing member 766 may be fabricated independently of the graft 731, asa complete toroid, which is then connected to an outer wall of thetubular member 734. In yet another form of the toroid-shaped sealingmember 866 (FIG. 18), the sealing member 866 may be formed to occupy themajority of the region between the vascular wall 32 and the tubularmember 834. In each of the embodiments, attachment systems 738, 838 likethose described above can be employed to affixed inferior as well asdistal ends of the graft devices 731, 831 to vasculature. Additionally,in each of the embodiments, holes 882 (See FIG. 18) may be configured inthe material defining the graft so that the sealing member fills withblood flowing through the graft.

Turning now to FIG. 19, there is shown a feed-tube 880 configured toprotrude through an aperture 882 formed in the tubular member 834 of thegraft 831 to gain access to an internal cavity defined by the sealingmember 840. The aperture 882 may be preformed or it can be made by thefeed-tube 880 piercing the graft. It is contemplated that such afeed-tube 880 can be used to deliver thrombogenic material to the repairsite. The feed-tube 880 may be delivered by a delivery cathetersimultaneously with delivery of the improved graft, and may be removedsimultaneously with the catheter. Alternatively, the feed-tube 880 canbe advanced within the graft 831, after the graft 831 has been deployedwithin vasculature.

In another embodiment (See FIGS. 20 and 21), the graft 931 of thepresent invention includes a sealing member that is formed from tuftedyarn 932, which may be impregnated with thrombogenic substance to inducecoagulating, and which is affixed to an outer wall of the tubular member934 of the graft 931. When the graft is deployed in a diseased vessel(not shown), the tufted yarn 932 operates to fill spaces between thevascular wall and the tubular member 934, thereby substantially forminga seal. In one form of the improved graft 931 having a tufted-yarnsealing member 934, the yarn 932 may be located on the outer surface ofthe tubular member 934 distal to the attachment system 938 (FIG. 20). Inanother aspect, the tufted-yarn sealing member 931 is located on theouter surface of the graft 931 between members defining the attachmentsystem 938 (See FIG. 21).

The tufted-yarn sealing member 932, may simply be attached to an outerwall of the graft 931 by stitching the yarn onto the wall of the tubularmember 934. The tufts of yarn may be made from the fabric making up thetubular member 934 itself. The fabric 940 (See FIG. 22) from which thegraft is manufactured may be woven so that weft threads (runninghorizontally) are omitted from certain zones 942 thereof. The lengths ofwarp threads (running vertically) which are not connected to each otherby weft threads are pulled radially outward to form a loop 944 (See FIG.23). The loops of warp thread 944 are cut at the apex of each loop 944,leaving single linear strands of yarn 946 (See FIG. 24)circumferentially protruding from the tubular member 934. The yarnthreads may be frayed to provide maximum surface area and if desired,impregnated with a thrombogenic substance.

It will be apparent from the foregoing that, while particular forms ofthe invention disclosed herein have been illustrated and described,various modifications can be made without departing from the spirit andscope of the invention. Accordingly, it is not intended that theinvention be limited, except as by the appended claims.

1. A graft comprising: a tubular member; a sealing member attached tosaid member, said sealing member having a generally toroidal shape thatencloses a generally toroid-shaped space and being configured tosurround said tubular member; and a separate compressible thrombogenicmaterial positioned within said generally toroid-shaped space of saidtoroid-shaped sealing member.
 2. The graft of claim 1, said tubularmember further comprising at least one aperture configured to permitblood within said tubular member to percolate into said generallytoroid-shaped space of said sealing member.
 3. The graft of claim 1,further comprising a device that delivers said separate compressiblethrombogenic material to said generally toroid-shaped space of saidtoroid-shaped sealing member.
 4. The graft of claim 1, furthercomprising a device that delivers filling material to said generallytoroid-shaped space of said toroid-shaped sealing member.
 5. The graftof claim 4, wherein said delivery device comprises a feed-tube.